Ytterbium

Ytterbium is a lustrous silver metal, and very malleable.  Ytterbium is of the rare earth family of elements and is reported to be the easiest of the rare earths to be rolled into thin sheets. Ytterbium, is formed by neutron irradiation of thullium. It is used as a portable radiograh source and foils are used to measure pressure and stress transducers. In it’s beta form, it is semiconductive at pressures above 16,000 atmospheres. One of ytterbium’s isotopes (¹⁷⁰Yb) is used as a portable x-ray source. Ytterbium is also used in lasers, phosphors, ceramic capacitors, ferrite devices, catalysts and as a dopant for garnets.

General Characteristics:

Atomic Weight: 173.04

Hardness: 17 HV

Poisson’s Ratio: 0.207

Strain-Hardening Exponent: 0.62

Density:

α phase, 6.903 g/cm³ at 23 ^oC

β phase, 6.966 g/cm³ at 24 ^oC

γ phase, 6.57 g/cm³ at 763 ^oC

Crystal Structure:

α phase: close-packed hexagonal, P6₃/mmc D^h₄; a=0.38799nm, c=0.63859nm at 24^oC.

β phase: face-centered cubic, Fm3m O^h₅; a=0.54848 nm at 24 ^oC

γ phase: body-centered cubic, Im3m O^h₉, a=0.444 nm at 763 ^oC

        Thermal Properties:

Melting Point: 824 ^oC

Boiling Point: 1196 ^oC

Phase Transformation Temperature:

α to β phase: A_s = 280 K

β to α phase: M_s ≅ 260 K

β to γ phase: 795 ^oC

Coefficient of Thermal Expansion (24^oC):

Linear: 26.3 μm/m ⋅ K

Linear along crystal axes: 26.3 μm/m ⋅ K along a axis

Volumetric: 78.9 x 10^-6 per K

Recrystallization Temperature: Approximately 300 ^oC

Thermal Conductivity: 38.5 W/m ⋅ K at 25 ^oC

Vapor Pressure:  

     301 ^oC: 0.001 Pa

     400 ^oC: 0.101 Pa

     776 ^oC:  1013 Pa

       Electrical Properties:

Electrical Resistivity: 250 nΩ ⋅ m at 25 ^oC; 10 nΩ ⋅ m at 4 K

Temperature of Superconductivity: Bulk ytterbium is not superconducting down to 0.015 K at atmospheric pressure.

Magnetic Susceptibility: Volume: 3.4 x 10^-6 mks at 17 ^oC

Thermal Neutron Cross Section: 37 b

       Corrosion Properties:

General Behavior: Ytterbium tarnishes slightly in moist air. It oxidizes slowly at elevated temperatures and reacts readily with hydrogen at 250 ^oC.

Resistance to Specific Corroding Agents: Ytterbium does not react with cold water, but it will tarnish in hot water. It reacts vigorously with dilute acids.

       Chemical Properties:

Ytterbium does not react with cold waer but will tarnishes in hot water and slightly in moist air. It oxidizes slowly at elevated temperatures and reacts readily with hydrogen at 250^o C.

       Mechancial Properties:

Tensile Properties (Room Temperature):

Tensile strength: 58 MPa

Yield strength: 7 MPa

Elongation: 43%

Reduction in area: 92%

Elastic Modulus (27 ^oC):  

Tension: 23.9 GPa

Shear:   9.9 GPa

Bulk: 30.5 GPa

Kinematic Liquid Viscosity: 0.430 mm²/s at 824 ^oC

Liquid Surface Tension: 0.320 N/m at 820 ^oC